1. Field of the Invention
Aspects of the present invention relate to a fusing device of an image forming apparatus, and more specifically, to a device which releases the pressure between rollers used in fusing an electrostatic latent image onto print material.
2. Description of the Related Art
Image forming apparatuses generally include a paper feed device which picks up paper from a feeding tray and feeds the paper along a feed path, a developing device which applies developing materials to an electrostatic latent image and develops the image, a transfer device which transfers the developed image onto the paper, and a fusing device which fuses the developed image onto a surface of the paper using heat and pressure.
FIG. 1 is a conceptual diagram explaining how a fixing roller in a related art fusing device is pressured and released. As shown in FIG. 1, a related art fusing device 1 includes a heating roller 2 which heats the paper, a pressure roller 3 which provides pressure when in contact with the heating roller 2, a pressure spring 4 which presses the rotational axis 3′ of the pressure roller 3 towards the heating roller 2 and maintains pressure on the pressure roller 3, and a pressure release member 6 disposed on the side of the rotational axis 3′ opposite the pressure spring 4 which releases pressure by pushing the rotational axis 3′ of the pressure roller 3 in the direction of the pressure spring 4 according to the rotation of a cam 5.
In such a configuration, the pressure supplied by the pressure roller 3 is maintained or released according to a rotation of the cam 5. That is, in order to release the pressure, the installed cam 5 rotates according to the method described above, and the pressure release member 6 releases the pressure by pushing the pressure roller 3 away from the heating roller 2 while rotating around a hinge 6′ towards the pressure spring 4. If the cam 5 rotates in the opposite direction, pressure is added to the pressure roller 3 using the pressure spring 4.
When the cover of the image forming apparatus is opened for purposes of maintenance or the like, for example, when paper is jammed between the heating roller 2 and the pressure roller 3 during image formation, or when the cover is closed in order to operate the image forming apparatus, the pressure roller 3 should be pressured or released, and so the opening and closing of the cover and the rotation of the cam should occur together.
In a related art fusing device, various mechanisms have been suggested in order to achieve this joint opening and closing. One suggested method uses a position detection sensor on the cam, and a power source which moves the cam so the position of the cam can be adjusted according to the opening and closing of the cover.
However, if a separate power source and position detection sensor are used as described above, these added components increase costs, and if the system suddenly halts during operation (for example, due to power being cut or a lightning strike), the reliability of the high pressure release function also drops, or additional costs are required to maintain reliability.
A second suggested method adjusts the angle of the cam according to whether the cover is open or shut by installing a lever attached to one side of the cover and connecting the other side of the cover to part of the cam. However, a problem with this second suggested method is that the reliability of the high pressure release function may drop if the configuration changes due to changes in the lever or cam caused by the high temperature of the heating roller or wear and tear of the cam parts.
An aspect of the present invention provides a fusing device in an image forming apparatus which resolves at least the above and/or other problems, reduces pressure in the fusing apparatus through the cover of the image forming apparatus being opened with minimal effort by the user, and increases pressure supplied by the pressure roller in a stable fashion when the cover is closed.
Another aspect of the present invention is to provide an image forming apparatus comprising the aforementioned fusing device.